Assume a system in which inverter units (power electronics devices) each have a communicating function, and automatic capacity change is performed in the cases including the extension of the system and the occurrence of abnormality while securing the flexibility of an operation, by employing an autonomous cooperative control such as a phase synchronization control of output power and power sharing control among a plurality of power electronics devices.
For example, for the purpose of increasing the output of power by causing a plurality of power electronics devices to operate in parallel, it is conceivable to have a function called phase synchronization control of output power. The function of phase synchronization control of output power is to prevent the occurrence of a cross current in an AC-side output (a reactive cross current flowing due to the difference in electromotive force, a synchronization cross current flowing due to the difference in phase difference of electromotive force, and a harmonic cross current flowing due to the difference in waveform of electromotive force). In this case, it is useful for increasing the throughput of power input/output that the plurality of power electronics devices determine an entity of control right, that is, a master (a device being a control entity)/a slave (a device being a controlled entity), and the master instructs the slave on power information for the phase synchronization control of output power or synchronization information (time synchronization information, frequency information). In the case where three or more power electronics devices are connected to the same power line, the actual values of individual devices with respect to the planned values thereof are hard to be recognized with only information from the power line, so the slave is synchronized with the master by exchanging power information using a communication control.
There has been disclosed a method in which a plurality of inverters each having a role of master/slave set in a fixed manner implement a parallel operation equivalent to the phase synchronization control of output power, by using synchronization through an optical communication line. In addition, there has been disclosed a method in which a device notifies apparatus information to a server through communication when connected to a system so as to dynamically set software of a server that performs a monitoring control to the device.
However, in the case where a plurality of power electronics device dynamically determine the roles of master/slave, since the devices separately operate in initial installation or in the occurrence of abnormality, the operation may be started in the state where a plurality of masters exist in the system if an established state of a logical configuration to control the power is not taken into consideration. In this case, it is difficult to centrally determine which power electronics device from which synchronization information is received to operate, so a function of the phase synchronization control of output power does not properly performed, which is problematic. These problem have not been able to be solved only by a simple combination of the conventional art (the roles of master/slave are fixed, the server centrally collects information to secure centralization of the information).
Furthermore, since the all conventional methods are assumed that the operating states range from in initial installation of the device to in operation, it is difficult to secure the flexibility of the operation and to maintain the throughput of power input/output by automatically performing fail-soft (fallback) to continue the power input/output in the event where an abnormality such as blackout (massive blackout) occurs, which is problematic.
As described above, the conventional arts have not disclosed a method of increasing the throughput of power input/output while securing the flexibility of an operation, in which a plurality of devices automatically change a logical configuration in operation scenes including the initial installation of the power electronics devices or the occurrence of abnormality after starting the operation.